Tension compensating assembly for mechanical control cables

ABSTRACT

A tension compensation assembly for a mechanical control cable. The tension compensation device has a housing with opposing ends. First and second sections of the control cable pass through but are attached at each end of the housing such that the sheaths of each section are coupled to the housing and reciprocable cable coaxially disposed in each control cable section extend into the housing. The cables are attached to opposing ends of a reciprocably disposed capsule or spring caps generally enclosing a spring. In operation, the capsule moves slidably within the housing over a predetermined travel and tension for the cables. However, if an over-tension condition is experienced, the capsule may bottom out at an end of the housing and the spring will either compress or extend, depending upon its design, thus allowing the effective length of the control cable assembly to increase, thus preventing the stretching or breaking of the cables or damage to cable end fittings.

This application is a divisional of U.S. patent application Ser. No.10/897,039, filed Jul. 22, 2004, the entire contents of which are herebyincorporated by reference thereto.

FIELD

The present invention relates generally to a tension compensationdevice, particularly to an apparatus for preventing stretching and/orbreakage of control cables and their end fittings during use.

BACKGROUND

A control cable typically comprises a flexible outer sheath encasing amulti-strand cable capable of free coaxial movement within the sheath.The control cable is installed such that the sheath is captively engagedat both ends and the inner cable is reciprocally movable within thefixed sheath. Control cables are commonly used to actuate remotelylocated latched devices in a vehicle and elsewhere. Examples of latcheddevice applications include hood releases, fuel door releases, trunkreleases, as well as passenger seat releases. In a typicalconfiguration, a first end of a cable is connected to a release lever orother control mechanism accessible to an occupant of a vehicle. A secondend of the inner cable is typically connected to a release mechanism ofthe latched device which, when engaged, maintains the device in a closedor latched position. To manually release the latched device, an operatoractuates the suitable release lever, causing the cable to tense withinthe control cable assembly. Once the tension on the control cableexceeds the force of the latching device, it unlatches.

A particular problem with the use of control cables to release latcheddevices is the potential for over-travel, or over-tensioning, of thecable components. Over-travel may occur when an operator actuates therelease lever and/or the latched device beyond their intended travellimits. This can cause excessive tension on the cables, which can leadto their stretching or breaking as well as causing damage to any endfittings attached thereto.

There is a need for a modification for a mechanical control cableassembly that is capable of being actuated through a normal range ofmovement and tension without restriction, yet prevents the cablecomponents from being stretched or broken due to over-travel by anassociated control mechanism or latch.

SUMMARY

A tension compensated control cable assembly is disclosed according tothe present invention. The tension compensation portion includes ahousing with opposing ends. First and second sheathed control cablesections pass through at each end of the housing such that the sheath ofeach section is captively retained by the housing at each end.Reciprocable cables, coaxially disposed within each control cablesection extends into the housing through their respective sheathes. Afirst cable within the first sheathed control cable passeslongitudinally through a first end of a capsule that is reciprocablydisposed within the housing. The first cable further passeslongitudinally through a compression spring and is coupled to a springcap. The spring is captively retained between the first end of thecapsule and the spring cap and is compressible within the capsule. Asecond cable within the second control cable passes through a second endof the housing and a second end of the capsule, where it is captivelyretained.

In operation, one embodiment of the invention operates such that thecompression spring remains in open-coil condition when in its unloadedstate. The first and second control cable sections are each attached toone of a latched device and a control mechanism, such as a mechanicallever, which can be either manually or machine operated. Applyingtension on one of the cable sections with the control mechanism resultsin longitudinal reciprocating movement of the capsule within thehousing, causing axial movement of the opposing cable, thereby actuatingand releasing the latched device. Thus, the first and second controlcable sections cooperate to function as a conventional, unitary controlcable when operated within the design limits of a particular latch andcable release application. However, in the event of an over-travel orover-tensioned condition, such that the tension on the cable exceeds apredetermined amount, the spring will compress as the spring cap isdrawn toward the first end of the capsule, increasing the effectivelength of the control cable assembly and thus limiting the tension onits components until a mechanical stop of either the release lever oractuated device is reached. As a result, the risk of stretching orbreaking of the control cable components and/or damage to their endfittings is greatly lessened.

The device comprises a first control cable section having an outersheath and a reciprocable inner cable and a second control cable sectionhaving an outer sheath and a reciprocable inner cable, and a coil springhaving first and second opposing ends, the first spring end beingcoupled to an end of the cable of the first control cable section andthe second spring end being coupled to an end of the cable of the secondcontrol cable section. A free end of the first control cable section iscoupled to a control mechanism and a free end of the second controlcable section is coupled to a remote latched device such that thecontrol cable assembly is effective to release the latched device uponactuation of the control mechanism. However, since the coils of thespring deform when the tension of the first and second cables exceeds apredetermined load, this reduces the risk of damage to the control cableassembly in the event of an over-travel condition.

The tension compensator comprises a housing having first and secondopposing ends. A capsule having first and second opposing ends isreciprocably disposed within the housing, the capsule including a springcap slidably disposed within the capsule and a compression springcaptively retained between the spring cap and the first end of thecapsule. A first control cable section comprises a first longitudinal,hollow sheath coupled to the first end of the housing, and a first cablereciprocally disposed within the first sheath, extending through thefirst end of the housing, the first end of the capsule and the spring,the end of the cable being coupled to the spring cap. A second controlcable section comprises a second longitudinal, hollow sheath passingthrough but captively retained by the second end of the housing, and asecond cable reciprocally disposed within the second sheath, extendingthrough the second end of the housing and being coupled to the secondend of the capsule. A free end of the first control cable section iscoupled to a control mechanism for exerting tension on the control cableassembly and a free end of the second control cable section is coupledto a latched device such that the actuation of the control mechanism iseffective to release the latched device. However, since the springcompresses when the tension of the first and second cable wires exceedsa predetermined amount, this reduces the risk of damage to the controlcable assembly in the event of an over-travel condition.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the inventive embodiments will become apparent tothose skilled in the art to which the embodiments relate from readingthe specification and claims with reference to the accompanyingdrawings, in which:

FIG. 1 is a view in section of a tension compensation assembly for acontrol cable according to an embodiment of the present invention;

FIG. 2 is a view in section of a tension compensation assembly for acontrol cable according to an embodiment of the present invention;

FIG. 3 is a view in section of a tension compensation assembly for acontrol cable according to an embodiment of the present invention;

FIG. 4A is a functional schematic diagram of the tension compensationassembly of FIG. 1;

FIG. 4B is a functional schematic diagram of the tension compensationassembly of FIG. 2;

FIG. 4C is a functional schematic diagram of the tension compensationassembly of FIG. 3;

FIG. 5 is a view in section of a tension compensation assembly for acontrol cable according to another embodiment of the present invention;and

FIG. 6 shows the general arrangement of a tension compensation assemblyoperatively employed with a latched device and a control mechanism.

DETAILED DESCRIPTION

In the discussion that follows, like numerals will be used to describefeatures having similar structure and/or function.

A control cable assembly 10 having a tension compensation assembly 11 isshown in FIG. 1 according to an embodiment of the present invention.Tension compensation assembly 11 is interposed between a first controlcable section 12 and a second control cable section 14. Tensioncompensation assembly 11 includes a housing 16, which may be one of avariety of shapes, such as generally cylindrical. First control cablesection 12 engages housing 16 at a first end 18. Likewise, secondcontrol cable section 14 engages housing 16 at a second, opposing end20.

First control cable section 12 includes a first sheath 22 and a first(inner) cable 24, the cable wire being disposed coaxially within thefirst sheath and longitudinally reciprocable. First sheath 22 is coupledto first end 18 of housing 16, while first cable 24 passes into housing16 through first end 18 and into a first end 26 of a capsule 28.Sheathed cable sections pass through first and second ends of thehousing and are captively retained using conventional means. Capsule 28is reciprocable within housing 16. First cable 24 passes generallycoaxially through the longitudinal axis of a compression-type open-coilspring 30 disposed within capsule 28, and then through a spring cap 32that is likewise reciprocable within the capsule. A first end fitting 34is coupled to an end of first cable 24, and is provided to exert forceupon spring cap 32 during actuation of a control mechanism 46 (see FIG.6). Although the embodiment of FIG. 1 is shown using an open-coil spring30, other materials having similar elastic properties may be employed toaccomplish the same or similar functions as the spring. Such materialsmay include a compressible material 35 such as rubber, foam rubber orother elastomers, as shown in FIG. 5.

Second control cable section 14 includes a second sheath 36 and a second(inner) cable 38, the second cable being disposed coaxially within thesecond sheath and longitudinally reciprocable. Second sheath 36 engagessecond end 20 of housing 16, while second cable 38 passes into housing16 through second end 20 and is coupled to a second end 42 of capsule 28by a second end fitting 40.

With continued reference to FIG. 1 together with FIG. 6, duringoperation of this embodiment of the invention, coil spring 30 is inopen-coil condition when not under a load. The spring rate of spring 30is preferably designed having a value such that the spring remainsessentially in an uncompressed state for the range of tension normallyexpected in a control cable for a particular latched device application.First control cable section 12 and second control cable section 14 areattached to one of a actuable latched device 44 and a control mechanism46, such as a lever, in any conventional manner. Exerting tension on oneof either cables 24, 38 by actuation of the control mechanism results ina tensing both of the cables causing slidable longitudinal movement ofcapsule 28 within housing 16. This results in a corresponding movementof the opposing cable, thereby actuating and releasing the connectedlatched device. Thus, first and second control cable sections 12, 14function as a unitary control cable when operated within the designlimits of a particular latched device.

However, in the event of an over-travel condition wherein the tensionexerted on cables 24, 38 exceeds a predetermined amount, capsule 28bottoms out against end 18 of housing 16, such as at an interior face19, which forms a first stop for the capsule. Alternatively, capsule 28may bottom out against end 20 of housing 16, such as at an interior face21, which forms a second stop for the capsule and is longitudinallyspaced apart from the first stop. In some embodiments either or bothends of capsule 28 may be shaped to correspond to the size and shape ofthe adjacent stop, such as capsule second end 42 and face 21. Spring 30compresses as first end fitting 34 and spring cap 32 slidably movetoward first end 26 of capsule 28, allowing the effective length ofcable wires 24, 38 to increase until a mechanical stop (not shown) ofthe control mechanism or remotely actuated device is reached. Thisprevents excessive tension that could stretch or break the cable wiresor damage connectors and end fittings (not shown) coupled to the cables.

A functional schematic diagram of control cable assembly 10 is shown inFIG. 4A. As can be seen, spring 30 is encased by capsule 28. Spring 30remains in an unloaded state and capsule 28 travels reciprocally withinits corresponding housing 16 (see FIG. 1) over the normal range oftravel and tension of cables 24, 38 for a particular control mechanismand latched device 46, 44, respectively (see FIG. 6). However, in theevent of an over-travel condition, one end of capsule 28 bottoms outagainst interior face 19 at end 18 of housing 16 (or, alternatively,against interior face 21 at end 20 of the housing) causing spring 30 tocompress as cable 24 is tensed in direction “A,” as depicted in FIG. 4A.The compression length of spring 30 is sufficiently long enough suchthat a mechanical stop of the control 46 and/or latched device 44 isreached before the spring becomes fully loaded (compressed, in thisembodiment).

Referring next to FIG. 2, a tension compensation assembly 101 for acontrol cable is shown according to an alternate embodiment of thepresent invention. Tension compensation assembly 101 is locatedintermediate a first control cable section 12 and a second control cablesection 14. First control cable section 12 engages housing 16 at a firstend 18. Conversely, second control cable section 14 engages housing 16at a second, opposing end 20. Housing 16 may be one of a variety ofshapes, such as generally cylindrical.

First control cable section 12 includes a first sheath 22 and a firstcable 24, the cable wire being disposed coaxially within the firstsheath and longitudinally reciprocable. First sheath 22 passes throughand is captively retained by first end 18 of housing 16, while firstcable 24 passes into housing 16 through first end 18 via first sheath.First cable 24 then passes through a first opening or slot 102 of afirst spring cap 104. First cable 24 passes through the openlongitudinal axis of a compression-type coil spring 30, which may behelical as shown, and then through a first opening or slot 106 of asecond spring cap 108. A first end fitting 34 is coupled to an end offirst cable 24, and is provided to exert force upon spring cap 108during actuation of a control mechanism (not shown).

Second control cable section 14 includes a second sheath 36 and a secondcable 38, the second cable being disposed coaxially within the secondsheath and longitudinally reciprocable. Second sheath 36 passes throughand is captively retained by second end 20 of housing 16, while secondcable 38 passes through a second opening or slot 110 of second springcap 108. Second cable 38 then passes generally through the center ofspring 30, generally parallel to first cable 24, and then through asecond opening or slot 112 of first spring cap 104. A second end fitting40 is coupled to the end of second cable 38, and is provided to exertforce upon spring cap 104 during actuation of a control mechanism (notshown). Spring 30 is thus captively retained between first and secondspring caps 104, 108 by cables 24, 38, the spring, cable wires, springcaps and end fittings forming a tension compensation assembly 114.

With continued reference to FIG. 2 together with FIG. 6, duringoperation of this embodiment compression spring 30 is in its open-coilcondition prior to the application of any significant load. The springrate of spring 30 is preferably designed having a value such that thespring remains essentially in its uncompressed (unloaded) state over thenormal range of tension expected in a control cable for a particularlatched device application. First control cable section 12 and secondcontrol cable section 14 are attached to one of a latched device 44 anda control mechanism 46, such as a lever, in any conventional manner.Exerting tension on one of cables 24, 38 with the control mechanismresults in slidable longitudinal movement of tension compensationassembly 114 within housing 16, resulting in axial movement of theopposing cable, thereby actuating and thus releasing the latched device.Thus, first and second control cable sections 12, 14 cooperate tofunction as a unitary control cable when operated within the designlimits of a particular remotely actuated latched device.

However, in the event of an over-travel condition, wherein the tensionon inner cables 24, 38 exceeds a predetermined amount, spring 30compresses as first and second spring caps 104, 108 move slidably towardeach other, allowing the effective overall length of cables 24, 38 toincrease until a mechanical stop (not shown) of the control mechanism 46or latched device 44 is reached, thus preventing excessive tension thatcould stretch or break the cables or damage connectors and end fittings34, 40 coupled to the ends of the cables.

A functional schematic diagram of control cable assembly 100 is shown inFIG. 4B. As can be seen, cables 24, 38 pass generally parallel to oneanother through the center of compression-type coil spring 30 inopposing directions, each being attached to end caps 104, 108 atopposing ends of the spring. Spring 30 remains substantiallyuncompressed as tension compensation assembly 114 travels reciprocallywithin housing 16 (see FIG. 2) over the normal range of travel andtension of cables 24, 38 for a particular control mechanism 46 andlatched device 44 application (see FIG. 6). However, in the event of anover-travel condition, spring 30 compresses as cable 24 is tensed indirection “A” and cable 38 is tensed in opposing direction “B”. Thecompression length of spring 30 is preferably such that a mechanicalstop of the control mechanism and/or remotely latched device is reachedbefore the spring reaches it fully loaded condition (fully compressed).

Referring now to FIG. 3, a control cable 200 having a tensioncompensation assembly 201 is shown according to yet another embodimentof the present invention. Tension compensation assembly 201 isinterposed between a first control cable section 12 and a generallyopposing second control cable section 14. Tension compensation assembly201 includes a housing 16, which may be one of a variety of shapes, suchas generally cylindrical. First control cable section 12 is coupled tohousing 16 at a first end 18. Likewise, second control cable section 14is coupled to housing 16 at a second, opposing end 20.

First control cable section 12 includes a first sheath 22 and a firstcable 24, the cable being disposed coaxially within the first sheath andlongitudinally reciprocable. First sheath 22 passes through and iscaptively engaged by first end 18 of housing 16, while first cable 24passes into housing 16 through first end 18 and into a first end 26 of acapsule 28. Capsule 28 is slidably reciprocable within housing 16. Cable24 passes through an endpiece 202. A first end fitting 34 is coupled toan end of first cable 24, and is provided to exert parting force uponspring cap 108 during actuation of the control mechanism (not shown).

Second control cable section 14 includes a second sheath 36 and a secondcable 38, the second cable being disposed coaxially within the secondsheath and longitudinally reciprocable. Second cable 38 passes intohousing 16 through second end 20 and is coupled to a second end 42 ofcapsule 28 by a second end fitting 40 affixed to an end of the secondcable. Both ends of a closed-coil extension spring 204 are preferablycaptively retained by end piece 202 and second end 42 of capsule 28. Aswill be appreciated, alternate elastic means may be substituted for theextension spring without departing from the spirit of the presentinvention. Such alternative source of energy storage may include rubberbands, polymer strips or other spring configurations.

With reference to FIG. 3 in combination with FIG. 6, during operation ofthis embodiment of the invention, extension spring 204 is in itsunloaded, closed-coil condition with the adjacent coils of the spring inclose proximity to or in contact with one another. The spring rate ofspring 204 may be configured in nearly any predetermined value such thatthe spring remains substantially in its unloaded profile for the rangeof tension expected in a control cable assembly for a given latchingapplication. First control cable section 12 and second control cablesection 14 are attached to one of a latched device 44 and a controlmechanism 46, such as a lever, in any conventional manner. Applyingtension on one of the cables 24, 38 with the control mechanism resultsin slidable longitudinal movement of capsule 28 within housing 16,resulting in a corresponding movement of the opposing cable section,thereby actuating and thus releasing the latched device. Thus, first andsecond control cable sections 12, 14 cooperate to function as a unitarycontrol cable when operated within the design limits of a particularlatched device application.

However, in the event of an over-travel condition, wherein the tensionon cable wires 24, 38 exceeds a predetermined load condition, end 26 ofcapsule 28 bottoms out against interior face 19 of end 18 of housing 16(or, alternatively, against interior face 21 at end 20 of the housing).At about that point, spring 204 extends as end piece 202 slidably movestoward first end 26 of capsule 28, allowing the effective combinedlength of cables 24, 38 to increase until a mechanical stop of thecontrol mechanism 46 or latched device 44 is reached, thus preventingexcessive tension that could stretch or break the cables or damageconnectors and end fittings (not shown) coupled thereto.

A functional schematic diagram of control cable assembly 200 is shown inFIG. 4C. As can be seen, extension spring 204 is enclosed by capsule 28.During normal operation, spring 204 remains in its substantiallyunloaded profile while capsule 28 travels reciprocally within housing 16(see FIG. 3) over the normal range of travel and tension of cables 24,38 for a particular control mechanism 46 and latched device 44 (see FIG.6). However, in the event of an over-travel condition, end 26 of capsule28 may bottom out against interior face 19 of end 18 of housing 16 (or,alternatively, against interior face 21 at end 20 of the housing) atabout which point spring 204 extends as cable 24 is tensed in direction“A,” as indicated in FIG. 4C. The extension length of spring 204 ispreferably such that a mechanical stop of the control mechanism and/orthe latched device is encountered prior to the spring reaching itselastic limit.

While this invention has been shown and described with respect todetailed embodiments thereof, it will be understood by those skilled inthe art that changes in form and detail thereof may be made withoutdeparting from the scope of the claims of the invention.

1. A tension compensation assembly for a mechanical control cableassembly, comprising: an elongated housing having a first and secondopposing, recessed housing end, the first recessed housing end extendingaway from an interior face that forms a first stop, the second recessedhousing end extending away from an interior face that forms a secondstop; a first end piece slidably disposed within the housing andconfigured to come into contact with the first stop; a second end pieceslidably disposed within the housing and configured to come into contactwith the second stop; a compressible spring located intermediate thefirst and second end pieces and being retained thereby, the first endpiece, second end piece and spring forming a tension compensation deviceslidably disposed within the housing; a first control cable sectioncomprising: a first longitudinal, hollow sheath, an end of the firstsheath being retained within within the first recessed housing end, anda first cable reciprocally disposed within the first sheath, extendingthrough the first end of the housing, through the first end piece, andentirely through the spring, the end of the first cable being coupled tothe second end piece; a second control cable section comprising: asecond longitudinal, hollow sheath, an end of the second sheath beingretained within the second recessed housing end, and a second cablereciprocally disposed within the second sheath, extending through thesecond end of the housing, through the second end piece, and entirelythrough the spring, the end of the second cable being coupled to thefirst end piece; a free end of the first control cable section beingcoupled to a control mechanism for exerting tension on the inner cablesof the control cable assembly when actuated and a free end of the secondcontrol cable section being coupled to a latched device such thatactuation of the control mechanism tenses the control cable assembly andreleases the latched device; and the tension compensation device freelyreciprocating with the first and second cables when the tension of theinner cables is below a predetermined threshold, one of the end piecescoming into contact with its stop and the spring compressing toeffectively increase the overall length of the control cable when thetension of the cables exceeds the threshold.
 2. The tension compensationassembly of claim 1 wherein the spring is a coiled spring.
 3. Thetension compensation assembly of claim 1 wherein the spring is anelastomer.
 4. The tension compensation assembly of claim 1 wherein thefirst cable is coupled to the second end piece with a first end fittingand the second cable is coupled to the first end piece with a second endfitting.
 5. A tension compensation assembly for a mechanical controlcable, comprising: an elongated housing having a first and secondopposing, recessed housing end, the first recessed housing end extendingaway from an interior face that forms a first stop, the second recessedhousing end extending away from an interior face that forms a secondstop; a capsule slidably disposed within the housing, the capsule havingfirst and second opposing capsule ends, the first capsule end beingconfigured to come into contact with the first stop and the secondcapsule end being configured to come into contact with the second stop,the capsule including: an endpiece slidably disposed within the capsule,and an extendable spring captively retained between the endpiece and thesecond end of the capsule; a first control cable section comprising: afirst longitudinal, hollow sheath, an end of the first sheath beingretained within the first recessed housing end and a first cablereciprocally disposed within the first sheath, extending through thefirst end of the housing and the first end of the capsule, the cablebeing coupled at its end to the endpiece; a second control cable sectioncomprising: a second longitudinal, hollow sheath, an end of the secondsheath being retained within the second recessed housing end and asecond cable reciprocally disposed within the second sheath, extendingthrough the second end of the housing, and being coupled at its end tothe second end of the capsule, a free end of the first control cablesection being coupled to a control mechanism for exerting tension on thecables within the control cable when actuated and a free end of thesecond control cable section being coupled to a latched device such thatactuation of the control mechanism is effective to release the latcheddevice; and the capsule freely reciprocating with the first and secondcables when the tension of the cables is below a predeterminedthreshold, one of the capsule ends coming into contact with its stop andthe spring expanding to effectively increase the overall length of thecontrol cable when the tension of the cables exceeds the threshold. 6.The tension compensation assembly of claim 5 wherein the spring is acoiled spring.
 7. The tension compensation assembly of claim 5 whereinthe spring is an elastomer.
 8. The tension compensation assembly ofclaim 5 wherein the first cable is coupled to the end piece with a firstend fitting and the second cable is coupled to the second end of thecapsule with a second end fitting.